A Soft Robotic Actuator System for In Vivo Modeling of Normal Pressure Hydrocephalus

OBJECTIVE

The intracranial pressure (ICP) affects the dynamics of cerebrospinal fluid (CSF) and its waveform contains information that is of clinical importance in medical conditions such as hydrocephalus. Active manipulation of the ICP waveform could enable the investigation of pathophysiological processes altering CSF dynamics and driving hydrocephalus.

METHODS

A soft robotic actuator system for intracranial pulse pressure amplification was developed to model normal pressure hydrocephalus in vivo. Different end actuators were designed for intraventricular implantation and manufactured by applying cyclic tensile loading on soft rubber tubing. Their mechanical properties were investigated, and the type that achieved the greatest pulse pressure amplification in an in vitro simulator of CSF dynamics was selected for application in vivo. A hydraulic actuation device based on a linear voice coil motor was developed to enable automated and fast operation of the end actuators. The combined system was validated in an acute ovine pilot in vivo study.

RESULTS

in vitro results show that variations in the used materials and manufacturing settings altered the end actuator's dynamic properties, such as the pressure-volume characteristics. In the in vivo model, a cardiac-gated actuation volume of 0.125 mL at a heart rate of 62 bpm caused an increase of 205% in mean peak-to-peak amplitude but only an increase of 1.3% in mean ICP.

CONCLUSION

The introduced soft robotic actuator system is capable of ICP waveform manipulation.

SIGNIFICANCE

Continuous amplification of the intracranial pulse pressure could enable in vivo modeling of normal pressure hydrocephalus and shunt system testing under pathophysiological conditions to improve therapy for hydrocephalus.

Radionuclide shuntography for cerebrospinal fluid shunt flow evaluation in adults

OBJECTIVE

Radionuclide shuntography (RS) performed using 99mTc-DTPA injected into the reservoir of CSF shunts enables evaluation of CSF flow for suspected shunt malfunctions. The goal of this study was to report the authors' institutional experience with RS and evaluate its utility and associated complications.

METHODS

The authors retrospectively reviewed all RS studies performed between November 2003 and June 2022. Patients with shunted hydrocephalus who were ≥ 18 years of age were included. Patients undergoing RS for evaluation of Ommaya reservoirs were excluded. Demographics, hydrocephalus etiology, presenting symptoms, study results, subsequent management, complications, and intraoperative diagnoses were recorded. Chi-square tests were reported for categorical variables and standard 2 × 2 contingency methods were used for sensitivity/specificity analysis.

RESULTS

The authors identified 211 RS procedures performed in 142 patients. The mean age at procedure was 55.6 ± 20.9 years (mean ± SD). Normal pressure hydrocephalus was the most common hydrocephalus etiology (37.0%), followed by congenital malformations (26.1%) and idiopathic intracranial hypertension (15.6%). Successful radionuclide injection was achieved in 207 studies (98.1%). Shunt patency was confirmed in 63.8% of successful injections, whereas malfunction was demonstrated in 27.1% and abnormally slow flow was seen in 9.2%. RS studies demonstrating shunt malfunction were more likely to result in subsequent revisions than were studies showing patency (86.6% vs 2.9%; p < 0.0001). The overall sensitivity and specificity of RS for detecting shunt malfunction was 92.3% and 96.2%, respectively. The median follow-up time was 29 months, with 151 cases having ≥ 6 months of follow-up. There were no complications or infections attributable to RS in this cohort.

CONCLUSIONS

RS is a useful and safe tool in the workup of shunt malfunction.

The Causal Effect of Gut Microbiota on the Development of Idiopathic Normal Pressure Hydrocephalus

BACKGROUND

Older people are particularly at risk for idiopathic normal pressure hydrocephalus (iNPH), a rare neurological condition without known risk factors. Several recent observational studies have reported that gut microbiota composition is associated with iNPH. However, the causal impact of gut microbiota on iNPH is unknown.

METHODS

Single nucleotide polymorphisms strongly associated with 196 gut microbiota (18,340 individuals) were selected as instrumental factors, and the results were iNPH data (322 cases of iNPH and 21,043 controls). Random effects, inverse variance weighting, weighted medians, and Mendelian random (MR) -Egger were used to investigate causal effects. The Cochran's Q test, funnel plot, leave-one-out analysis, MR-Egger intercept test, and outlier (Global) test were employed in the sensitivity analysis to identify and compensate for the presence of pleiotropy. The MR-Steiger test also examined the hypothesised connection between exposure and result.

RESULTS

Our findings are mainly based on the inverse variance weighting approach and support a causal relationship between 6 gut microbial taxa and iNPH. We observed an inverse association between the Eubacterium fissicatena group (P = 0.007) and Lactococcus (P = 0.038) and iNPH, whereas Adlercreutzia (P = 0.029), Dialister (P = 0.040), Romboutsia (P = 0.027), Sutterella (P = 0.019) may be associated with an increased risk of iNPH. The results of the sensitivity analysis were robust.

CONCLUSIONS

Our findings suggest that certain gut bacteria may enhance iNPH risk. Research is required to determine whether the societal impact of iNPH is lessened in older people by sensible control of their gut microbiota.

Are brain displacements and pressures within the parenchyma induced by surface pressure differences? A computational modelling study

The intracranial pressure is implicated in many homeostatic processes in the brain and is a fundamental parameter in several diseases such as e.g. idiopathic normal pressure hydrocephalus. The presence of a small but persistent pulsatile intracranial pulsatile transmantle pressure gradient (on the order of a few mmHg/m at peak) has recently been demonstrated in hydrocephalus subjects. A key question is whether pulsatile intracranial pressure and displacements can be induced by a small pressure gradient originating from the brain surface alone. In this study, we model the brain parenchyma as either a linearly elastic or a poroelastic medium, and impose a pulsatile pressure gradient acting between the ventricular and the pial surfaces but no additional external forces. Using this high-resolution physics-based model, we use in vivo pulsatile pressure gradients from subjects with idiopathic normal pressure hydrocephalus to compute parenchyma displacement, volume change, fluid pressure, and fluid flux. The resulting displacement field is pulsatile and in qualitatively and quantitatively good agreement with the literature, both with elastic and poroelastic models. However, the pulsatile forces on the boundaries are not sufficient for pressure pulse propagation through the brain parenchyma. Our results suggest that pressure differences at the brain surface, originating e.g. from pulsating arteries surrounding the brain, are not alone sufficient to drive interstitial fluid flow within the brain parenchyma and that potential pressure gradients found within the parenchyma rather arise from a large portion of the blood vessel network, including smaller blood vessels within the brain parenchyma itself.

Mass spectrometry in cerebrospinal fluid uncovers association of glycolysis biomarkers with Alzheimer's disease in a large clinical sample

Alzheimer's disease (AD) is a complex and heterogeneous neurodegenerative disorder with contributions from multiple pathophysiological pathways. One of the long-recognized and important features of AD is disrupted cerebral glucose metabolism, but the underlying molecular basis remains unclear. In this study, unbiased mass spectrometry was used to survey CSF from a large clinical cohort, comparing patients who are either cognitively unimpaired (CU; n = 68), suffering from mild-cognitive impairment or dementia from AD (MCI-AD, n = 95; DEM-AD, n = 72), or other causes (MCI-other, n = 77; DEM-other, n = 23), or Normal Pressure Hydrocephalus (NPH, n = 57). The results revealed changes related to altered glucose metabolism. In particular, two glycolytic enzymes, pyruvate kinase (PKM) and aldolase A (ALDOA), were found to be upregulated in CSF from patients with AD compared to those with other neurological conditions. Increases in full-length PKM and ALDOA levels in CSF were confirmed with immunoblotting. Levels of these enzymes furthermore correlated negatively with CSF glucose in matching CSF samples. PKM levels were also found to be increased in AD in publicly available brain-tissue data. These results indicate that ALDOA and PKM may act as technically-robust potential biomarkers of glucose metabolism dysregulation in AD.

Fluctuations in Upper and Lower Body Movement during Walking in Normal Pressure Hydrocephalus and Parkinson's Disease Assessed by Motion Capture with a Smartphone Application, TDPT-GT

We aimed to capture the fluctuations in the dynamics of body positions and find the characteristics of them in patients with idiopathic normal pressure hydrocephalus (iNPH) and Parkinson's disease (PD). With the motion-capture application (TDPT-GT) generating 30 Hz coordinates at 27 points on the body, walking in a circle 1 m in diameter was recorded for 23 of iNPH, 23 of PD, and 92 controls. For 128 frames of calculated distances from the navel to the other points, after the Fourier transforms, the slopes (the representatives of fractality) were obtained from the graph plotting the power spectral density against the frequency in log-log coordinates. Differences in the average slopes were tested by one-way ANOVA and multiple comparisons between every two groups. A decrease in the absolute slope value indicates a departure from the 1/f noise characteristic observed in healthy variations. Significant differences in the patient groups and controls were found in all body positions, where patients always showed smaller absolute values. Our system could measure the whole body's movement and temporal variations during walking. The impaired fluctuations of body movement in the upper and lower body may contribute to gait and balance disorders in patients.

Normalized Power Variance: A new Field Orthogonal to Power in EEG Analysis

To date, electroencephalogram (EEG) has been used in the diagnosis of epilepsy, dementia, and disturbance of consciousness via the inspection of EEG waves and identification of abnormal electrical discharges and slowing of basic waves. In addition, EEG power analysis combined with a source estimation method like exact-low-resolution-brain-electromagnetic-tomography (eLORETA), which calculates the power of cortical electrical activity from EEG data, has been widely used to investigate cortical electrical activity in neuropsychiatric diseases. However, the recently developed field of mathematics "information geometry" indicates that EEG has another dimension orthogonal to power dimension - that of normalized power variance (NPV). In addition, by introducing the idea of information geometry, a significantly faster convergent estimator of NPV was obtained. Research into this NPV coordinate has been limited thus far. In this study, we applied this NPV analysis of eLORETA to idiopathic normal pressure hydrocephalus (iNPH) patients prior to a cerebrospinal fluid (CSF) shunt operation, where traditional power analysis could not detect any difference associated with CSF shunt operation outcome. Our NPV analysis of eLORETA detected significantly higher NPV values at the high convexity area in the beta frequency band between 17 shunt responders and 19 non-responders. Considering our present and past research findings about NPV, we also discuss the advantage of this application of NPV representing a sensitive early warning signal of cortical impairment. Overall, our findings demonstrated that EEG has another dimension - that of NPV, which contains a lot of information about cortical electrical activity that can be useful in clinical practice.

Increasing brain N-acetylneuraminic acid alleviates hydrocephalus-induced neurological deficits

AIMS

This metabolomic study aimed to evaluate the role of N-acetylneuraminic acid (Neu5Ac) in the neurological deficits of normal pressure hydrocephalus (NPH) and its potential therapeutic effect.

METHODS

We analyzed the metabolic profiles of NPH using cerebrospinal fluid with multivariate and univariate statistical analyses in a set of 42 NPH patients and 38 controls. We further correlated the levels of differential metabolites with severity-related clinical parameters, including the normal pressure hydrocephalus grading scale (NPHGS). We then established kaolin-induced hydrocephalus in mice and treated them using N-acetylmannosamine (ManNAc), a precursor of Neu5Ac. We examined brain Neu5Ac, astrocyte polarization, demyelination, and neurobehavioral outcomes to explore its therapeutic effect.

RESULTS

Three metabolites were significantly altered in NPH patients. Only decreased Neu5Ac levels were correlated with NPHGS scores. Decreased brain Neu5Ac levels have been observed in hydrocephalic mice. Increasing brain Neu5Ac by ManNAc suppressed the activation of astrocytes and promoted their transition from A1 to A2 polarization. ManNAc also attenuated the periventricular white matter demyelination and improved neurobehavioral outcomes in hydrocephalic mice.

CONCLUSION

Increasing brain Neu5Ac improved the neurological outcomes associated with the regulation of astrocyte polarization and the suppression of demyelination in hydrocephalic mice, which may be a potential therapeutic strategy for NPH.

Cerebrospinal fluid production rate in various pathological conditions: a preliminary study

INTRODUCTION

The cerebrospinal fluid (CSF) production rate in humans is not clearly defined but is estimated to be 18-24 ml/h (Trevisi et al Croat Med J 55(4):377-387 (24); Casey and Vries Childs Nerv Syst 5(5):332-334 (8)). A frequent clinical observation is that patients often drain higher volumes of CSF than can be explained by the assumed 'normal' CSF production rate (PRcsf). In the National Hospital for Neurology and Neurosurgery PRcsf was recorded in a variety of common neurosurgical pathologies using LiquoGuard7, an automated peristaltic pump that accurately controls CSF drainage and maintains a pre-set CSF pressure.

METHODS

A prospective observational study was performed from September 2021 onwards, on all patients in the National Hospital for Neurology and Neurosurgery who required CSF drainage as part of their ongoing treatment. The external drain was connected to a LiquoGuard7 pump (Möller Medical GmbH, Fulda, Germany), and the internal software of LiquoGuard7 was used to measure PRcsf. Statistical analysis used SPSS (version 25.0, IBM) by paired t test, comparing measured rates to hypothetical 'normal' CSF production rates calculated and published by Ekstedt (16-34ml/h) (Ekstedt J Neurol Neurosurg Psychiatry 41(4):345-353 (14)), assuming a similar distribution.

RESULTS

PRcsf was calculated in 164 patients. Suspected normal pressure hydrocephalus (n=41): PRcsf of 79ml/h±20SD (p<0.0001). Post-surgical CSF leak (n=26): PRcsf of 90ml/h±20SD (p<0.0001). Subarachnoid haemorrhage (n=34): PRcsf of 143ml/h±9SD (p<0.0001). Intracerebral haemorrhage (n=22): PRcsf of 137ml/h±20SD (p<0.0001). Spinal lesions (n=7): PRcsf of 130ml/h±20SD (p<0.0032). Pituitary adenomas (n=10): PRcsf of 29 ml/h±9SD (p<0.049). Idiopathic intracranial hypertension (n=15): PRcsf of 86ml/h±10SD (p<0.0001). Decompensated long-standing overt ventriculomegaly (n=4): PRcsf of 65ml/h±10SD (p<0.0001). Cerebral infection (n=5): PRcsf of 90ml/h±20SD (p<0.0001).

CONCLUSION

Net CSF production rate may be higher than expected in many conditions, as measured with new device LiquoGuard7 through the study of net flow rate, which may have implications for clinical decisions on CSF diversion. The conventional understanding of CSF production and circulation does not explain the findings of this study. More extensive studies are needed to validate this technique.

Sagittal Spinal Deformity in Patients with Idiopathic Normal Pressure Hydrocephalus

AIM

To measure the baseline spinopelvic parameters and characterize the sagittal, and coronal plane deformities in patients with idiopathic normal pressure hydrocephalus (iNPH).

MATERIAL AND METHODS

We analyzed a series of patients at one academic institution who underwent ventriculoperitoneal shunting for iNPH with pre-shunt standing full length x-rays. The series of patients was enrolled consecutively to minimize selection bias. We quantified comorbid sagittal plane spinal deformity based on the Scoliosis Research Society-Schwab classification system by assessing pelvic incidence and lumbar lordosis mismatch (PI-LL), pelvic tilt (PT), and sagittal vertical axis (SVA).

RESULTS

Seventeen patients (59% male) were included in this study. Mean (± standard deviation) age was 74 ± 5.3 years with a body mass index (BMI) of 30 ± 4.5 kg/m < sup > 2< sup > . Six patients (35%) had marked sagittal plane spinal deformity by at least one parameter: five (29%) had greater than 20˚ PI-LL mismatch, three (18%) had > 9.5 cm SVA, and one (6%) had PT greater than 30˚. Additionally, the thoracic kyphosis exceeded the lumbar lordosis in nine patients (53%).

CONCLUSION

Positive sagittal balance, with thoracic kyphosis exceeding lumbar lordosis, is common in iNPH patients. This may lead to postural instability, especially in patients whose gait does not improve following shunting. These patients may warrant further investigation and workup, including full length standing x-rays. Future studies should assess for improvement in the sagittal plane parameters following shunt placement.

Quantitative Evans index estimation using ultrasonographic measurement of the optic nerve sheath diameter in supine and upright position

OBJECTIVES

We aimed to quantitatively assess Evans index (EI) using ultrasonographic optic nerve sheath diameter (ONSD) measurements in supine and upright position in normal pressure hydrocephalus (NPH) patients.

METHODS

Ultrasonographically ONSD was measured in a supine and upright position before and 4-5 days after the ventriculoperitoneal shunt surgery. The changes of the ONSD between supine and upright positions were calculated as ∆ONSD = sONSD-uONSD and as the variation ONSD_V = 100% × [(sONSD - uONSD)/sONSD]. Multiple linear regression analyses were conducted to assess associations between EI and the variation of ONSD. We derived the mathematical function to predict EI. Bland-Altman analysis was applied to evaluate the accuracy and precision of the EI prediction.

RESULTS

Thirteen adult patients (mean age 61.8 ± 11.1 (SD) years; 6 (46%) female) undergone VP shunt implantation for NPH. The mean EI was 0.432 (95% CI, 0.393-0.471) preoperatively and 0.419 (95% CI, 0.373-0.466) postoperatively (p = 0.066). There is a decrease of the ONSD during positional changes from supine to upright position and pre- and postoperative EI correlated with preoperative variation ONSD_V1 (r =  - 0.610 and - 0.648, p < 0.05). The mathematical function for preoperative EI estimation was EI_preop = 0.504 - 0.022 × ONSD_V1 + 0.101 × gender (M = 0; W = 1), (Durbin-Watson value = 1.94), and for postoperative was EI_postop = 0.487 - 0.022 × ONSD_V1 + 0.117 × gender; (Durbin-Watson value 2.23).

CONCLUSIONS

Ultrasonographic ONSD measurements in supine and upright position provide a potential method to quantify EI that can be conducted at the bedside.

Normal-pressure hydrocephalus: A rare cause of reversible dementia

ABSTRACT

Normal-pressure hydrocephalus (NPH) is characterized by the clinical triad of dementia, gait instability, and urinary incontinence. The estimated annual incidence is 1.8 cases in 100,000 persons, making NPH a rare diagnosis and uncommon cause of dementia. NPH is a form of communicating hydrocephalus that can easily be missed in older adults with multiple comorbidities, so clinicians must exclude reversible causes of dementia before diagnosing irreversible causes such as Alzheimer disease.

Data-Driven Investigation of Gait Patterns in Individuals Affected by Normal Pressure Hydrocephalus

Normal pressure hydrocephalus (NPH) is a chronic and progressive disease that affects predominantly elderly subjects. The most prevalent symptoms are gait disorders, generally determined by visual observation or measurements taken in complex laboratory environments. However, controlled testing environments can have a significant influence on the way subjects walk and hinder the identification of natural walking characteristics. The study aimed to investigate the differences in walking patterns between a controlled environment (10 m walking test) and real-world environment (72 h recording) based on measurements taken via a wearable gait assessment device. We tested whether real-world environment measurements can be beneficial for the identification of gait disorders by performing a comparison of patients’ gait parameters with an aged-matched control group in both environments. Subsequently, we implemented four machine learning classifiers to inspect the individual strides’ profiles. Our results on twenty young subjects, twenty elderly subjects and twelve NPH patients indicate that patients exhibited a considerable difference between the two environments, in particular gait speed (p-value p=0.0073), stride length (p-value p=0.0073), foot clearance (p-value p=0.0117) and swing/stance ratio (p-value p=0.0098). Importantly, measurements taken in real-world environments yield a better discrimination of NPH patients compared to the controlled setting. Finally, the use of stride classifiers provides promise in the identification of strides affected by motion disorders.

Compliance of the cerebrospinal space: comparison of three methods

BACKGROUND

Cerebrospinal compliance describes the ability of the cerebrospinal space to buffer changes in volume. Diminished compliance is associated with increased risk of potentially threatening increases in intracranial pressure (ICP) when changes in cerebrospinal volume occur. However, despite various methods of estimation proposed so far, compliance is seldom used in clinical practice. This study aimed to compare three measures of cerebrospinal compliance.

METHODS

ICP recordings from 36 normal-pressure hydrocephalus patients who underwent infusion tests with parallel recording of transcranial Doppler blood flow velocity were retrospectively analysed. Three methods were used to calculate compliance estimates during changes in the mean ICP induced by infusion of fluid into the cerebrospinal fluid space: (a) based on Marmarou's model of cerebrospinal fluid dynamics (C_CSF), (b) based on the evaluation of changes in cerebral arterial blood volume (C_CaBV), and (c) based on the amplitudes of peaks P1 and P2 of ICP pulse waveform (C_P1/P2).

RESULTS

Increase in ICP caused a significant decrease in all compliance estimates (p < 0.0001). Time courses of compliance estimators were strongly positively correlated with each other (group-averaged Spearman correlation coefficients: 0.94 [0.88-0.97] for C_CSF vs. C_CaBV, 0.77 [0.63-0.91] for C_CSF vs. C_P1/P2, and 0.68 [0.48-0.91] for C_CaBV vs. C_P1/P2).

CONCLUSIONS

Indirect methods, C_CaBV and C_P1/P2, allow for the assessment of relative changes in cerebrospinal compliance and produce results exhibiting good correlation with the direct method of volumetric manipulation. This opens the possibility of monitoring relative changes in compliance continuously.

Unusual side effects of levetiracetam

We present a 75-year-old man who was admitted to our hospital due to 4 months of general deterioration, gait disturbance and cognition impairment which appeared very close to the start of levetiracetam (LEV) as a new antiepileptic drug. Brain CT shows central and less peripheral atrophy of brain, and diagnosis of normal pressure hydrocephalus was raised; however, removal of 30 cc of cerebrospinal fluid (CSF) by lumbar puncture in order to amend walking did not lead to gait improvement. After excluding metabolic, vascular, infection, inflammatory and other reasons explaining his status. Thinking that may be any correlation between LEV added in the last months and his clinical condition, we stopped LEV. Several days after that, there is marked improvement in his general sensation, alertness and cognitive status and there is marked improvement in walking balance to the point of being able to walk without the use of walker or cane or help from other person. Certain cognitive impairment and gait difficulties are not known as side effects of LEV treatment.

Inpatient diagnoses of idiopathic normal pressure hydrocephalus in the United States: Demographic and socioeconomic disparities

INTRODUCTION

Epidemiology provides an avenue for identifying disease pathogenesis, hence determining national incidence, along with socioeconomic and demographic variables involved in iNPH, can provide direction in elucidating the etiology and addressing healthcare inequalities.

METHODS

To investigate incidence (per 100,000) of iNPH diagnoses applied to the inpatient population, with respect to sex, age, income, residence, and race/ethnicity, we queried the largest American administrative dataset (2008-2016), the National (Nationwide) Inpatient Sample (NIS), which surveys 20% of United States (US) discharges.

RESULTS

Annual national inpatient incidence (with 25th and 75th quartiles) for iNPH diagnoses was 2.86 (2.72, 2.93). Males had an inpatient incidence of 3.27 (3.11, 3.39), higher (p = 0.008) than female at 2.45 (2.41, 2.47). Amongst age groups inpatient incidence varied (p = 0.000004) and was largest amongst the 85+ group at 18.81 (16.40, 19.95). Individuals with middle/high income had an inpatient incidence of 2.96 (2.77, 3.06), higher (p = 0.008) than the 2.37 (2.24, 2.53) of low-income patients. Depending on whether patients lived in urban, suburban, or rural communities, inpatient incidence diverged (p = 0.01) as follows, respectively: 2.65; 2.66; 3.036. Amongst race/ethnicity (p = 0.000003), inpatient incidence for Whites, Blacks, Hispanics, Asian/Pacific Islanders, and Native Americans were as follows, respectively: 3.88 (3.69, 3.93), 1.065 (1.015, 1.14); 0.82 (0.76, 0.85); 0.43 (0.33, 0.52); 0.027 (0.026, 0.12).

CONCLUSION

In the US, inpatient incidence for iNPH diagnoses exhibited disparities between socioeconomic and demographic strata, emphasizing a healthcare inequality. Disproportionately, diagnoses were applied most to patients who were White, male, 65 and older, middle/high income, and living in rural communities.

Normal pressure hydrocephalus and CSF tap test response: the gait phenotype matters

This study compared gait speed changes after CSF tap test in patients with idiopathic normal pressure hydrocephalus presenting with various gait phenotypes (frontal, parkinsonian, normal, or other). All patients improved, except those with parkinsonian gait.

[Urinary dysfunction in idiopathic normal pressure hydrocephalus]

Urinary incontinence (UI) is a significant burden in the elderly and their caregivers when assessed by quality-of-life measures, early institutionalization, or health economics. UI is well known as a clinical triad for the diagnosis of normal pressure hydrocephalus (NPH). However, other than UI, NPH patients commonly have urinary urgency/frequency (overactive bladder: OAB), and less commonly, voiding difficulty. Fourteen percent of the patients (either women or men) have post-void residual > 100 ml. The most common urodynamic abnormality is detrusor overactivity (DO), which was noted in 95% of patients. The underlying pathophysiology for OAB/DO in patients with NPH seems to be decreased cerebral blood flow in the right frontal cortex, and to a lesser extent, altered basal ganglia function. Functional UI can overlap the OAB/DO due secondary to impaired cognition/initiative, immobility, or disturbed consciousness in this disorder.

On the optimal opening pressure of hydrostatic valves in cases of idiopathic normal-pressure hydrocephalus: a prospective randomized study with 123 patients

Does the opening pressure of hydrostatic shunts influence the clinical outcome for patients suffering from idiopathic normal-pressure hydrocephalus (NPH)? Between September 1997 and January 2003, 123 patients with idiopathic NPH were surgically treated by implanting a hydrostatic shunt at the Departments of Neurosurgery of the Unfallkrankenhaus Berlin and the University Homburg/Saar. As part of a prospective randomized study, all patients were examined preoperatively, postoperatively, and 1 year after the intervention. Forty-three percent of the patients showed a very good outcome, 25% good outcome, 20% fair outcome, and 12% poor outcome 1 year after the shunt implantation. Patients treated with an opening pressure rating of 50 mmH2O in the low-pressure stage of the gravitational valve showed a better outcome than those with an opening pressure of 100 or 130 mmH2O. According to present knowledge, hydrostatic shunts with an opening pressure of 50 mmH2O for the low-pressure stage are the best option for patients with idiopathic NPH. Due to the prompt switching function when the patient changes posture (lying down, standing, sitting, slanting etc.), the Miethke gravity-assisted valve (GAV) is more suitable in such cases than the Miethke Dual-Switch valve (DSV).

The effect of ketanserin on ICP and CBF in patients with normal-pressure hydrocephalus

Eight patients with normal-pressure hydrocephalus were studied. Intracranial pressure (ICP) and mean arterial blood pressure (MAP) were measured continuously before and during administration of ketanserin i.v. (10 mg bolus followed by an infusion of 3 mg over a 60-min period, 6 mg over the next 30 min, and 12 mg over the last 30 min). The mean baseline MAP and ICP were 103 and 8 mm Hg, respectively. Five minutes after the bolus dose, the maximum decrease in MAP occurred (mean, 17 mm Hg; p < 0.05). The maximum ICP (10 mm Hg) occurred at 5 min and at 100 min after the bolus dose but was not significantly different from the baseline value. There was no change in relative global cerebral blood flow (CBF) expressed as 1/(arteriovenous oxygen difference). It is concluded that ketanserin in a clinically recommended dose decreases blood pressure without significantly influencing the ICP or CBF.

Long-term prognosis of patients with central cerebral ventricular enlargement. A fifth follow-up study of 100 patients with a 3rd ventricle measuring 12 mm or more in width

One hundred patients with a 3rd ventricle width of 12 mm or more were examined for the fifth time in 1976 after an average observation period of 20.8 years. On first admission, a predominant aetiological factor was found in 27 cases. Two patients had air-encephalogrophical findings indicating normal pressure hydrocephalus. One of these had a shunt operation, however, without improvement. Seventy-one patients had died, 7 patients were in need of care and supervision, 11 patients were unable to work, the remaining 11 were able to work to some extent. The group studied had a significantly increased mortality rate. The causes of death were divided into three groups: 1. Probably related to the underlying brain disorder; 2. Related to those in an average Norwegian population; and 3. Minor disorder usually not leading to death. The following factors indicated a poor long-term prognosis: 1. Serious associated disease; 2. A relatively high age; 3. Associated cardiovascular disease; 4. Marked degree of ventricular enlargement; 5. Marked enlargement of the temporal horns; 6. Many and/or marked neurological signs; and 7. Prognosis intellectual deterioration.

A study of confabulation

Confabulation consequent to organic amnesia is a well-described clinical finding. A number of plausible theories of confabulation have been proposed, but the various claims and counterclaims have not been systematically tested. A standardized test battery that included four different kinds of questions plus measures of suggestibility and the tendency to utilize external cues was administered to ten amnesic patients who demonstrated varying degrees of confabulation. One additional patient, whose clinical condition changed dramatically during his hospital course, received the battery on a number of occasions. Differences among patients were found in overall performance, degree of confabulation, and ability to use cues. Hypothesized relationships between confabulation and suggestibility, degree of memory disorder, and degree of disorientation were not confirmed. However, confabulation proved to be strongly related to the inability to withhold answers, to monitor one's own responses and to provide verbal self-corrections. These results suggest a tentative model of the process of confabulation as well as a number of useful clinical signs indicationg recovery from amnesia.

[Communicating hydrocephalus. Clinical aspects, diagnosis, pathogenesis]

A description of the clinical symptoms of the communicating hydrocephalus (normal-pressure hydrocephalus = NPH) is given: progressive psycho-organic alterations, ataxia, tetraspastic signs, urinary incontinence, without increased intracranial pressure. Diagnosis can be confirmed by use of pneumencephalography, isotope-cisternography and tomography of the brain by use of a water-solubile contrast fluid. Skull radiographs. EEG, testing of liquor and psychological examinations are of less diagnostic value. The illness is the result of a disturbance of liquor resorption and circulation. In this context there is to differentiate between cases of known (Hydrocephalus communicans obstructivus = HCO) and unknown etiology (Hydrocephalus communicans non obstructivus = HCNO). The group of cases with unknown etiology represents the central part of cases of normal-pressure hydrocephalus (NPH). The prognosis after a ventricular shunt-procedure is here worse than in the group of cases with known etiology. For differential diagnosis presenil dementia, cerebrovascular insufficiency, intracranial tumors and reactive and psychotic depressions are to be considered.

Cystic cavum veli interpositi associated with normal or low pressure hydrocephalus

A new clinical syndrome, characterized by progressive increase in head size (without intracranial hypertension), variable delay in milestones, moderate ventricular dilation, and the presence of a cavum veli interpositi is herein described. The arteriographic and venographic signs are suggestive, but not diagnostic, of the presence of a cavum veli interpositi. Pneumoencephalography, with adequate filling of the subarachnoid spaces and ventricles, is essential to confirming the diagnosis. Cerebrospinal fluid shunting appears to result in an improvement, but the results cannot as yet be considered definitive since only 10 of our 29 patients were shunted.